faft: Ensure DevMode and TryFwB tests going back to their original modes

The DevMode and TryFwB tests may not go back to their original modes
on test failures, like DevMode may end with a different mode, TryFwB
may end with firmware B booting. This CL is to add a check to ensure
these tests going back.

BUG=chromium-os:35902
TEST=run_remote_tests.sh --board link --remote dut DevMode TryFwB/control$

Change-Id: If312fdc53a5210e29c42042e56d18a78df2ffd68
Reviewed-on: https://gerrit.chromium.org/gerrit/37334
Reviewed-by: Vic Yang <victoryang@chromium.org>
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
2 files changed